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The mechanical reliability of optical fiber is critically important for many engine sensor applications where the fiber is subjected to cyclic loading, high temperature, and oily, acidic environments. We have investigated the effect of buffer coatings on the cyclic fatigue behavior of fused silica fibers. Aluminum, polyimide, uvcurable epoxy acrylate, and Tefzel coated fibers were tested at room temperature and after exposure to heat and oil. Cyclic fatigue was measured using a test fixture that simulates the motion of a piston in an internal combustion engine. The results indicate that the selection of buffer coating is an important consideration in determining mechanical reliability of optical fibers in this application.

Nine alkyl 2-picolyl ketones were prepared by the interaction of 2-picolyllithium and the requisite methyl ester. Physical properties were determined, and hydantoin and picrate derivatives of these ketones were prepared.

We have developed a magnetron sputter coating method to continuously coat silica optical fibers with a dual layer coating of Inconel 625 alloy and platinum. The coating process is performed on-line as the fiber is drawn to minimize the rapid strength degradation of the silica due to attack by moisture in the air. Because of the modular design of the sputter equipment, the process is well suited for the deposition of a wide variety of metals and is readily adapted for scale-up. Multimode optical fibers were produced with coatings up to 0.5 microns in thickness consisting of an adhesion layer of Inconel and an outer layer of platinum. The coatings are adherent and remain mechanically intact after thermal cycling between room temperature and 2000° F in vacuum. Approximate tensile strengths of 145 to 290 Kpsi have been measured. These attributes make this sputter coated fiber a promising candidate for use in high temperature environments.

Die Reaktion (nach Goldberg) von Picolyl‐Li (I) mit den Estern (II) in Äther liefert die Ketone (III) (20‐5 8% Ausbeute), die mit KCN und NH4‐carbonat bei 70°C (Badtemperatur) in die Hydantoine (IV) übergeführt werden.

A major factor that determines the reliability of silica optical fibers in high temperature environments is the nature of the coating material and process. We have demonstrated coating silica fibers using dc planar magnetron sputter deposition. A unique feature of this method is the ability to hermetically coat fiber with high temperature metals that are impossible to deposit by conventional fiber coating processes. Such coatings are deposited uniformly in thickness with relatively high efficiencies. The results obtained with adherent, pinhole-free copper coatings indicate that the process is suitable for on-line coating of optical fibers as they are drawn.

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